Due to changes in medical practice over the last few years, the use of medical oxygen and other medical gases has increased. Many of these gases, like Entonox® (a mixture of nitrous oxide and oxygen, commonly used for pain relief), have to be kept in specific conditions and temperature ranges, to ensure they are effective in use and don’t separate.
This presents a real challenge for facilities managers. Many gas bottle stores are located outside, away from a building, generally in the form of a cage of some description. This may satisfy Health & Safety but isn’t always suitable for the specific environmental needs of some of the gases and may also leave them vulnerable to theft.
So how can you create safe, secure storage whilst still complying with Health & Safety legislation? The Estates Department of Carmarthenshire’s Hywel Dda University Health Board had that same question, and approached Construction Specialites (CS) for the solution.
Housing potentially volatile gases within any building poses a risk of Deflagration – an explosion that propagates slower than the speed of sound.
Deflagrations can happen in any confined space containing hazardous materials and are caused by ignition of a fuel – a gas, liquid or solid material capable of reacting with an oxidising medium.
The human cost of these incidents can be high, and the financial damage of explosions can be damaging, with the structural repair and refurbishment costs and increased insurance premiums.
The Solution: CS Explovent
The only field testable and resettable explosion and pressure relief venting system. Fully code compliant and maintenance free, CS Explovent offers peace of mind and verifiable performance.
Explovent wall panels are designed to be the weakest part of the external structure, and are factory-calibrated to release at very low design pressures (usually between 0.25kPa to 2kPa / 0.0025bar and 0.02 bar). As the Explovent experiences pressure rise, it opens quickly allowing the rapidly expanding, heated gasses to be released to the outside, and thereby diffuses a potential explosion.
The hinged panels are made of insulated aluminium, mounted in an aluminium frame, and finished in a durable fluorocarbon polymeric coating. CS Explovent can also be supplied with a translucent polycarbonate panel insert to reduce the need for artificial lighting.
Why Explovent® Wall Venting Panels
- ATEX compliant and CE marked
- Lightweight, low inertia panels for quick venting
- Field testable via non-destructive means
- Precisely pressure calibrated at the factory
- Unique hinge system & resettable latch
- Smooth surfaces reduce dust accumulation
- Hold open devices protects from implosion
- Rigorously tested to ensure safety & compliance
The Health and Safety at Work etc Act 1974
Places a general duty on employers to ensure the safety of both employees and other people from the risks arising from work activity, so far as is reasonably practicable.
Directive 99/92 (ATEX 137 or the ATEX Workplace Directive)
The directive gives minimum requirements for improving the Health & Safety protection of workers potentially at risk for explosive atmospheres. In the UK, this is implemented through the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR).
The Dangerous Substances and Explosive Atmospheres Regulations (DSEAR)
DSEAR (2002) requires employers to assess the Health & Safety risks arising from dangerous substances – materials that “could, if not properly controlled, cause harm to people as a result of a fire or explosion or corrosion of metal”. These include solvents, paints, varnishes, flammable gases (such as liquid petroleum gas), dust, pressurised gas and substances corrosive to metal. DSEAR requires employers to put measures in place to “either remove those risks or, where this is not possible, control them”.
Directive 94/9/EC (ATEX 95 or the ATEX Equipment Directive)
Covering equipment and protective systems intended for use in potentially explosive atmospheres, this directive allows trade of ATEX equipment across the EU, removing the need for separate testing and documentation for each Member State. Certification ensures equipment or protective systems are fit for purpose and that adequate information is supplied to ensure they can be used safely.
The Equipment and Protective Systems Intended for use in Potentially Explosive Atmospheres
In the UK, ATEX 95 is implemented through BIS Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996 (SI 1996/192), which came into force in 2003. EPS covers a wide range of equipment, including explosion venting systems. It requires testing by an independent body and equipment must be CE marked.
BS EN 14797: 2006 Explosion venting devices
This European Standard specifies the requirements for venting devices used to protect enclosures against the major effects of internal explosions arising from the rapid burning of suspended dust, vapour or gas.
BS EN 14491:2012 Dust explosion venting protective systems
This European Standard specifies the requirements of design for the selection of dust explosion venting protective systems.
BS EN 14994: 2007 Gas explosion venting protective systems
This European Standard specifies the basic design requirements of design for the selection of a gas explosion venting protective system.
NFPA 68 Standard on Explosion Protection by Deflagration Venting (2013)
The US National Fire Protection Association is recognised as the leading global authority on explosive events. This document provides specific recommendations for the design, location, installation, maintenance and operation of explosion vents.
FM Global FM 4440 Approval Standard for Explosion Venting Systems
The standard sets out the performance requirements for explosion venting systems – examined for their ability to remain in place under normal conditions but to fail at pre-determined pressure levels. It also covers wall fasteners to secure wall panels to buildings, plus latches and magnetic release devices.
FM Global Property Loss Prevention Data Sheet 1-44 Damage-Limiting Construction
This document provides guidelines for the design and construction of building components, including explosion venting panels, based on the pressures, room areas and the type of substances being used or stored in the building.
HTM 02-01 Medical gas pipeline systems – Part B: Operational management
The Department of Health’s Health Technical Memoranda (HTMs) provide best practice engineering standards for healthcare providers. HTM 02-01 Part B covers the operational management and maintenance of medical gases supplied by pipeline.
It includes guidance for gas cylinder store construction and the materials that should be used, including the requirement for “Blow-out” panels. These, it says, “should be fitted into the external wall of any ground level store constructed as part of, and under, another building. These panels should be sited at a minimum height of 2.3m above ground level”.
British Compressed Gases Association Code of Practice 44: The Storage of gas cylinders
This code of practice provides advice and guidance for the safe storage of gas cylinders, including recommendations for construction of stores. For indoor stores, it states: “Where there is a risk of explosion, the design of the building should ensure at least half of the longest wall or half of the roof area should be made of open mesh or lightweight materials to provide explosion relief. The relief should be designed and positioned such that any hazards are minimized in the event of an explosion.”
HSG51 Storage of flammable liquids in containers
This guidance is for those responsible for the safe storage of flammable liquids in containers up to 1,000 litre capacity. It covers the fire and explosion hazards and is designed to be used with DSEAR.
Natural Environment Research Council guidance: Safe storage and installation of gas cylinders
This guidance is aimed at institutions carrying out NERC activities – providing special gases for laboratory equipment, engineering use in the field and medical applications. For storage of gas cylinders inside a building, it recommends consideration be given to the need for explosion relief.